JP6769040B2 - How to inspect electronic devices - Google Patents

Description

The present invention relates to an inspection method for inspecting a heat dissipation function of the heat conduction member with a temperature of the heat generating component detectable electronic device.

Conventionally, an electronic device in which a heat generating element such as a switching element and a thermistor or the like for measuring the temperature at which the heat generating element generates heat is mounted on a substrate is known.
The electronic device described in Patent Document 1 detects the temperature of the heat-generating component by using a thermistor, and limits the amount of current supplied to the heat-generating component so that the heat-generating component does not heat beyond the permissible temperature. There is.
Further, in this electronic device, a heat radiating gel as a heat conductive material is filled between the heat sink and the heat generating component provided on the side opposite to the substrate with respect to the heat generating component. As a result, the heat generated by the heat generating component is dissipated to the heat sink via the heat radiating gel.

Japanese Unexamined Patent Publication No. 2015-126809

However, Patent Document 1 does not describe the position where the thermistor is attached when a plurality of heat generating components are mounted on the substrate. If the thermistor is mounted in the vicinity of a heat-generating component whose heat-generating temperature is relatively low among a plurality of heat-generating components, it may be difficult to accurately detect the temperature of the heat-generating component whose heat-generating temperature is higher than that of the heat-generating component. I am concerned.

Further, in this electronic device, after assembling the substrate and the heat sink, it is not possible to visually recognize whether or not the heat radiating gel is surely filled between the heat sink and the heat generating component. Therefore, if the heat-dissipating gel is not filled between the heat sink and the heat-generating component, or if the heat-dissipating gel filled therein has an insufficient heat-dissipating function, the heat generated by the heat-generating component is appropriately dissipated to the heat sink. There is concern that it will not be done.

The present invention has been made in view of the above points, and provides an electronic device capable of accurately detecting the temperature of a heat generating component, and an inspection method for inspecting the heat dissipation function of the heat conductive material included in the electronic device. The purpose is.

The present invention is an inspection method for inspecting the heat dissipation function of a heat conductive material included in an electronic device. This inspection method includes a first temperature acquisition step, a second temperature acquisition step, a determination step, an upper limit threshold setting step, and an inspection step. In the first temperature acquisition step, in the first reference product having the configuration of the electronic device, the temperature detected by the detection unit when the electric power is supplied to the heat generating component in a predetermined current pattern is acquired. In the second temperature acquisition step, in the second reference product obtained by removing the heat conductive material from the configuration of the electronic device, the temperature detected by the detection unit when power is supplied to the heat generating component in a predetermined current pattern is acquired. In the determination step, it is determined whether or not the difference between the temperature acquired in the first temperature acquisition step and the temperature acquired in the second temperature acquisition step is larger than a predetermined threshold value. In the upper limit threshold setting step, when the difference between the temperature acquired in the first temperature acquisition step and the temperature acquired in the second temperature acquisition step is larger than a predetermined threshold value, the temperature detected in the first temperature acquisition step and the second temperature The upper threshold is set by the temperature between the temperature detected in the acquisition step. In the inspection step, electric power is supplied to the heat-generating component of the inspection product in a predetermined current pattern, and it is inspected whether or not the temperature detected by the detection unit included in the inspection product is lower than the upper limit threshold value.

As a result, the upper limit threshold is set by the temperature between the temperature detected in the first temperature acquisition step and the temperature detected in the second temperature acquisition step. Therefore, when there is a tolerance in the temperature characteristics of the inspection product in the inspection step. But, due to the temperature difference between the temperature and the upper limit threshold value obtained by the first temperature acquisition step, it is possible to absorb the tolerances. Therefore, according to this inspection method, it is possible to suppress erroneous detection in the inspection of the heat dissipation function of the heat conductive material included in the inspection product .

It is sectional drawing of the electronic apparatus according to 1st Embodiment of this invention. It is a top view in the II direction of FIG. It is an enlarged view of the part III of FIG. It is a circuit block diagram of the electronic device by 1st Embodiment. It is a flowchart of the inspection method of the electronic device by 1st Embodiment. This is an example of a current pattern used in the method for inspecting an electronic device according to the first embodiment. It is a graph which shows an example of the temperature characteristic of the electronic apparatus by 1st Embodiment. It is a graph which shows an example of the temperature characteristic of the electronic apparatus by 1st Embodiment. It is a flowchart of the inspection method of the electronic device by 1st Embodiment. It is a top view of the electronic apparatus according to 2nd Embodiment. It is a top view of the electronic apparatus according to 3rd Embodiment.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. All of the drawings are schematic views, and the aspect ratio and the like are changed as appropriate, and the description of some parts is omitted.

[First Embodiment]
The first embodiment of the present invention is shown in FIGS. 1 to 9. The electronic device 1 of the present embodiment can be applied to control of various products and the like. Here, as an example thereof, an electronic device 1 that drives and controls a motor 2 that generates an assist torque for assisting steering by a driver in an electric power steering device of a vehicle will be described.

(Control device configuration)
First, the configuration of the electronic device 1 will be described.
As shown in FIGS. 1 and 2, the electronic device 1 includes a substrate 10, a plurality of switching elements 20, a heat sink 30, a microcomputer 40, a thermistor 50, and the like.

The substrate 10 is a printed wiring board such as FR-4, and is formed in a substantially rectangular shape. The substrate 10 is fixed to the heat sink 30 by screws 31 inserted into the holes provided at the four corners and the center.
The heat sink 30 is made of a material having good thermal conductivity such as aluminum and has a predetermined heat mass. The heat sink 30 also functions as a housing for supporting the substrate 10 and the like.
In the following description, the surface of the substrate 10 on the heat sink 30 side is referred to as the first surface 11, and the surface on the side opposite to the heat sink 30 is referred to as the second surface 12. That is, the heat sink 30 is located on the first surface 11 side of the substrate 10.

Four switching elements 20, a shunt resistor 25, a capacitor 26, a relay 27, a connector 28, and the like are mounted on the first surface 11 of the substrate 10.
The switching element 20 is, for example, a MOSFET (metal oxide semiconductor field effect transistor). An IGBT (insulated gate bipolar transistor) or the like may be applied as the switching element 20. The four switching elements 20 and the shunt resistor 25 correspond to an example of a "heating component".

The four switching elements 20 and the shunt resistor 25 are housed in a recess 32 provided in the heat sink 30. A heat radiating gel 33 as a heat conductive material is filled between the switching element 20, the shunt resistor 25, the first surface 11 of the substrate 10 on which they are mounted, and the inner wall of the recess 32 of the heat sink 30. The heat radiating gel 33 has a function of transferring the heat generated by the switching element 20 and the shunt resistor 25 to the heat sink 30 by energization or the like.

Large electronic components such as the capacitor 26 and the relay 27 are housed in a storage chamber 34 provided in the heat sink 30. The recess 32 of the heat sink 30 for accommodating the switching element 20 and the like described above is formed to be shallower than the accommodating chamber 34 for accommodating large electronic components. As a result, the heat sink 30 secures a large amount of heat mass at the location where the recess 32 for accommodating the switching element 20 and the like is formed, and enhances the heat dissipation efficiency of the switching element 20 and the like.
The connector 28 is used for electrical connection with the motor 2, the battery 3 (see FIG. 4), various sensors of the vehicle, and the like.

A microcomputer 40, a custom IC 41, a thermistor 50 as a temperature detecting element, and the like are mounted on the second surface 12 of the substrate 10. The microcomputer 40 and the custom IC 41 are both semiconductor packages having a CPU, ROM, RAM, I / O, and the like. The microcomputer 40 and the custom IC 41 control the rotational drive of the motor 2 by controlling the operation of the switching element 20 based on the signals from the sensors provided in each part of the vehicle.
The microcomputer 40 and the custom IC 41 are provided at positions separated from each other in the longitudinal direction of the substrate 10 with respect to electronic components such as a switching element 20, a shunt resistor 25, a capacitor 26, and a relay 27 through which a relatively large current flows. This makes it possible to reduce the influence of noise caused by the large current flowing through the switching element 20 and the like.

The thermistor 50 is mounted on the second surface 12 with the substrate 10 interposed therebetween at a position close to the switching elements 21 and 22 having a relatively high heat generation temperature among the four switching elements 20. It is more preferable that the thermistor 50 is mounted at a position close to the switching elements 21 and 22 having the highest temperature rise among the four switching elements 20.
The thermistor 50 is, for example, an NTC or PTC thermistor, and the resistance value changes depending on the temperature change of the thermistor 50 itself. By providing the thermistor 50 on the second surface 12 of the substrate 10, it is possible to prevent the heat of the thermistor 50 itself from being transferred to the heat sink 30 via the heat radiation gel 33.
The output from the thermistor 50 is input to the microcomputer 40. The microcomputer 40 functions as a detection unit that detects the temperature of the thermistor 50 by the output of the thermistor 50. The temperature detected by the microcomputer 40 as the detection unit is the temperature of the thermistor 50, and the temperature corresponds to the heat generation temperature of the switching element 20 or the temperature of the substrate 10 at the position where the thermistor 50 is provided.

Next, an example of the circuit configuration of the electronic device 1 of the present embodiment will be described with reference to FIG. In FIG. 4, for convenience, the motor 2 is described in the electronic device 1, but the motor 2 is provided outside the electronic device 1 separately from the electronic device 1.
The four switching elements 20 form, for example, an H-bridge circuit. In the following description, the two switching elements 20 connected to the power supply side will be referred to as the first switching element 21 and the second switching element 22, respectively, and the two switching elements 20 connected to the ground side will be referred to as the first switching element 20, respectively. It will be referred to as a 3 switching element 23 and a 4th switching element 24.

In this H-bridge circuit, the first and third switching elements 21 and 23 are connected in series, and the second and fourth switching elements 22 and 24 are connected in series. Further, the first and third switching elements 21 and 23 connected in series and the second and fourth switching elements 22 and 24 connected in series are connected in parallel.
The connection points of the first and second switching elements 21 and 22 are connected to the positive electrode of the battery 3 via the relay 27 and the choke coil 29. The choke coil 29 reduces noise.
The capacitor 26 connected in parallel with the battery 3 stores electric charges to assist the power supply to the switching element 20 and suppress noise components such as surge voltage.
The connection points of the third and fourth switching elements 23 and 24 are connected to the negative electrode of the battery 3 via the shunt resistor 25. The shunt resistor 25 is used to detect the current applied to the motor 2.
The DC motor 2 is connected between the connection points of the first and third switching elements 21 and 23 and the connection points of the second and fourth switching elements 22 and 24.

Here, the operation of the H-bridge circuit will be described. The H-bridge circuit is driven and controlled by a control signal from a control unit 42 composed of a microcomputer 40, a custom IC 41, and the like.
First, when the control unit 42 instantly turns off the third switching element 23, turns off the second switching element 22, turns on the first switching element 21, and turns on the fourth switching element 24 in this order, the positive electrode of the battery 3 is used. Current flows from the choke coil 29, the relay 27, the first switching element 21, the motor 2, the fourth switching element 24, the shunt resistance 25, and the negative electrode of the battery 3 in this order. As a result, the motor 2 rotates in a predetermined direction (hereinafter referred to as "positive direction").

Next, when the control unit 42 instantly turns off the fourth switching element 24, turns off the first switching element 21, turns on the second switching element 22, and turns on the third switching element 23 in this order, the battery 3 A current flows from the positive electrode to the choke coil 29, the relay 27, the second switching element 22, the motor 2, the third switching element 23, the shunt resistor 25, and the negative electrode of the battery 3 in this order. As a result, the motor 2 rotates in a direction opposite to the forward direction (hereinafter referred to as "reverse direction").
By the way, as described above, when the control unit 42 changes the rotation direction of the motor 2 from the forward direction to the reverse direction, if the control unit 42 turns off the fourth switching element 24, the first switching element 21 and the motor 2 until then. The current flowing in the order of the fourth switching element 24 is circulated in the order of the first switching element 21, the motor 2, and the second switching element 22 for a moment.

Such current circulation also occurs when the rotation direction of the motor 2 is changed from the reverse direction to the forward direction. That is, when the control unit 42 turns off the third switching element 23, the current that has been flowing in the order of the second switching element 22, the motor 2, and the third switching element 23 until then is only for a moment, and the second switching element 22 The motor 2 and the first switching element 21 flow in this order. Therefore, in the H-bridge circuit, the heat generation temperature of the first switching element 21 and the second switching element 22 connected to the power supply side is the heat generation temperature of the third switching element 23 and the fourth switching element 24 connected to the ground side. Will be higher than.

Therefore, in the present embodiment, as shown in FIG. 3, the position where the thermistor 50 is mounted is set to a position close to the switching elements 21 and 22 having a relatively high heat generation temperature among the four switching elements 20. In FIG. 3, the first switching element 21 and the second switching element 22 mounted on the first surface 11 of the substrate 10 are shown by broken lines, and the thermistor 50 mounted on the second surface 12 of the substrate 10 and the thermistor 50 thereof. The wiring pattern 51 of the board 10 on which the thermistor 50 is mounted is shown by a solid line. Hereinafter, the wiring pattern 51 of the substrate 10 on which the thermistor 50 is mounted is referred to as a heat receiving wiring pattern 51.

The first switching element 21 and the second switching element 22 mounted on the first surface 11 of the substrate 10 have drain terminals 211,221, source terminals 212, 222, and gate terminals 213, 223, respectively. In FIG. 3, a wiring pattern for connecting the drain terminals 211 and 221 and the source terminals 212 and 222 of the first switching element 21 and the second switching element 22 is provided on the first surface 11 of the substrate 10, and the wiring pattern thereof. The region where heat generation is large is shown by the alternate long and short dash line F. Hereinafter, the wiring pattern of the substrate 10 to which the drain terminals 211 and 221 and the source terminals 212 and 222 of the first switching element 21 and the second switching element 22 are connected is referred to as a power wiring pattern 14.

Here, the heat receiving wiring pattern 51 provided on the second surface 12 is provided at a position facing the power wiring pattern 14 provided on the first surface 11. As a result, the heat transferred from the first switching element 21 and the second switching element 22 to the power wiring pattern 14 via the drain terminals 211 and 221 and the source terminals 212 and 222 is transferred to the heat receiving wiring pattern 51 facing the power wiring pattern 14. ..
Further, the heat receiving wiring pattern 51 is provided so as to straddle a plurality of power wiring patterns 14 to which the drain terminals 211 and 221 and the source terminals 212 and 222 of the first switching element 21 and the second switching element 22 are connected, respectively. Has been done. Thereby, it is possible to detect the heat generation temperature of both the first switching element 21 and the second switching element 22 by using one thermistor 50.

However, in the configuration of the electronic device 1 described above, after assembling the substrate 10 and the heat sink 30, it is possible to visually recognize whether or not the heat radiation gel 33 is surely filled between the heat sink 30 and the switching element 20. Can not. Even if it can be confirmed that the heat radiating gel 33 is filled by making a hole in the substrate 10, it is difficult to guarantee whether or not the heat radiating gel 33 surely exhibits the heat radiating function. is there. Therefore, in the present embodiment, whether or not the heat radiating gel 33 included in the electronic device 1 exhibits the heat radiating function is inspected by the inspection method described below.

(Inspection method)
An inspection method regarding the heat dissipation function of the heat dissipation gel 33 in the electronic device 1 will be described with reference to FIGS. 5 to 9.
In this inspection method, first, the upper limit threshold value Tth_max used when inspecting a plurality of electronic devices 1 is set by using two reference products. Next, the heat dissipation function of the heat dissipation gel 33 included in the plurality of electronic devices 1 is inspected using the upper limit threshold value Tth_max.

The method of setting the above-mentioned upper limit threshold value Tth_max is shown in the flowchart of FIG.
First, as the current pattern selection step (S1), the current pattern used for the inspection is selected. Examples of the current pattern are those shown in FIGS. 6 (A) to 6 (D). In the first current pattern selection step (S1), it is assumed that, for example, the current pattern shown in FIG. 6A is selected as the nth current pattern.

Next, as the first temperature acquisition step (S2), a first reference product having the same configuration as the configuration of the electronic device 1 described above is prepared. Then, the current pattern shown in FIG. 6A is applied to the switching element 20 of the first reference product. At this time, the temperature detected by the microcomputer 40 based on the output of the thermistor 50 is acquired by the inspection machine 5 (see FIGS. 1 and 2). The solid line P in FIG. 7A is an example of the temperature change acquired by the inspection machine 5.

Subsequently, as the second temperature acquisition step (S3), a second reference product (not shown) having a configuration in which the heat radiation gel 33 is removed from the configuration of the electronic device 1 described above is prepared. That is, the second reference product does not include the heat dissipation gel 33. Then, the same current pattern as in the first temperature acquisition step (S2) is applied to the switching element 20 of the second reference product. At this time, the temperature detected by the microcomputer 40 based on the output of the thermistor 50 is acquired by the inspection machine 5. The solid line Q in FIG. 7A is an example of the temperature change acquired by the inspection machine 5.

Next, as the determination step (S4), first, the temperature acquired after a lapse of a certain period of time K seconds after applying the current pattern in the first temperature acquisition step (S2) (hereinafter referred to as "first acquisition temperature") A. And the difference M from the temperature (hereinafter referred to as "second acquisition temperature") B acquired after a lapse of a certain time K seconds after applying the current pattern in the second temperature acquisition step (S3) is obtained. Then, it is determined whether or not the temperature difference M is larger than the predetermined threshold value α. The predetermined threshold value α is appropriately set according to the tolerance of the temperature characteristics of the plurality of electronic devices 1. When the temperature difference M is larger than the predetermined threshold value α, the process proceeds to the current pattern determination step (S5).

In the current pattern determination step (S5), the heat dissipation gel provided in the plurality of electronic devices 1 is the current pattern used in the first temperature acquisition step (S2), the first temperature acquisition step (S3), and the determination step (S4) described above. It is determined as a current pattern when inspecting the heat dissipation function of 33.
Subsequently, in the upper limit threshold setting step (S6), the upper limit threshold value Tth_max used when inspecting the heat dissipation function of the heat dissipation gel 33 included in the plurality of electronic devices 1 is set. As shown in FIG. 7A, this upper limit threshold value Tth_max is set to a temperature between the first acquisition temperature A and the acquisition temperature B.

On the other hand, as shown in FIG. 7B, the temperature of the thermistor 50 changes as shown by the solid line R in the first temperature acquisition step (S2) described above, and the thermistor 50 changes in the second temperature acquisition step (S3) described above. It is conceivable that the temperature of is changed as shown by the solid line S. In this case, in the determination step (S4), the difference N between the first acquisition temperature C and the second acquisition temperature D may be smaller than the predetermined threshold value α. When the temperature difference N is larger than the predetermined threshold value α, the process shifts to the current pattern change step (S7).

In the current pattern change step (S7), the nth current pattern used for the inspection is incremented by 1 so that n = n + 1. After that, the process returns to the current pattern selection step (S1) again. In the next current pattern selection step (S1), for example, the current pattern shown in FIG. 6B is selected as the nth current pattern. In this way, the current pattern supplied to the heat generating component of the electronic device 1 is changed in the first temperature acquisition step (S2) and the second temperature acquisition step (S3).

After that, various processes are performed as illustrated in FIGS. 6 (A) to 6 (D) until the difference between the first acquisition temperature and the second acquisition temperature becomes larger than the predetermined threshold value α in the determination step (S4). Each step (S1 to S4 and S7) is repeatedly executed using the current pattern of.
As a result, the upper limit threshold value Tth_max used when inspecting the plurality of electronic devices 1 and the current pattern at that time are set.
As shown in FIG. 8, the lower limit threshold value Tth_min may be set together with the upper limit threshold value Tth_max used when inspecting a plurality of electronic devices 1.

Subsequently, a method of inspecting the heat dissipation function of the heat dissipation gel 33 included in the plurality of electronic devices 1 will be described with reference to the flowchart of FIG.
First, as the current pattern selection step (S10), the current pattern determined in the above-mentioned current pattern determination step (S5) is selected as the current pattern to be used for this inspection.

Next, as the inspection step (S11), the current pattern selected in the current pattern selection step (S10) is applied to the switching element 20 of the predetermined electronic device 1. Then, it is determined whether or not the temperature acquired after a lapse of a certain period of time K seconds after applying the current pattern (hereinafter referred to as "inspection temperature") is smaller than the upper limit threshold value Tth_max set in the upper limit threshold value setting step (S6). ..

When the inspection temperature is smaller than the upper limit threshold value Tth_max, it is determined that the heat dissipation function of the heat dissipation gel 33 included in the predetermined electronic device 1 is functioning effectively (S12), and the inspection of the predetermined electronic device 1 is completed. ..
On the other hand, when the inspection temperature is larger than the upper limit threshold value Tth_max, the predetermined electronic device 1 does not have the heat radiating gel 33, or even if the heat radiating gel 33 is provided, the heat radiating function does not function effectively. (S13), and the inspection of the predetermined electronic device 1 is completed.
Subsequently, by the processing of S10 to S13, the inspection of the plurality of electronic devices 1 is sequentially performed.

(Action effect)
The electronic device 1 of the present embodiment has the following effects.
(1) In the present embodiment, the thermistor 50 is provided on the second surface 12 opposite to the first surface 11 on which the heat radiation gel 33 is applied to the substrate 10, so that the heat of the thermistor 50 itself causes the heat radiation gel 33. It is possible to prevent heat from being dissipated to the heat sink 30 via the heat sink 30. Further, in the thermistor 50, the temperature of the thermistor 50 itself changes due to a temperature change of the switching elements 21 and 22 having a relatively high heat generation temperature among the plurality of switching elements 20. Therefore, the electronic device 1 can accurately detect the temperature of the switching elements 21 and 22 by the output of the thermistor 50. As a result, the electronic device 1 can appropriately limit the amount of current supplied to all the switching elements 21 to 24.
It is more preferable that the thermistor 50 is mounted at a position close to the switching elements 21 and 22 having the highest temperature rise among the plurality of switching elements 20.

(2) In the present embodiment, the substrate 10 is provided with a heat receiving wiring pattern 51 on which the thermistor 50 is mounted on the second surface 12 which is opposite to the first surface 11 on which the switching element 20 is mounted.
As a result, the heat generated by the switching element 20 can be received by the heat receiving wiring pattern 51, and the temperature of the thermista 50 can be changed by the heat. Therefore, the electronic device 1 can sensitively measure the steep temperature rise of the switching element 20 by the thermistor 50.

(3) In the present embodiment, the heat receiving wiring pattern 51 is located at a position facing the power wiring pattern 14 to which the drain terminals 211 and 221 or the source terminals 212 and 222 of the switching elements 21 and 22 having a relatively high heat generation temperature are connected. Provided.
As a result, the heat generated by the switching element 20 can be transferred from the power wiring pattern 14 to the heat receiving wiring pattern 51, and the temperature of the thermistor 50 can be changed by the heat. Therefore, the electronic device 1 can sensitively measure the steep temperature rise of the switching element 20 by the thermistor 50.

(4) In the present embodiment, the heat receiving wiring pattern 51 is provided so as to straddle the plurality of power wiring patterns 14 at positions facing the plurality of power wiring patterns 14 to which the plurality of switching elements 20 are connected.
Thereby, it is possible to detect the temperatures of the plurality of switching elements 20 by using one thermistor 50.

(5) In the present embodiment, the switching elements 21 and 22 having a relatively high heat generation temperature are the switching elements 21 and 22 connected to the power supply side among the plurality of switching elements 20 constituting the H-bridge circuit. ..
This makes it possible to easily identify the switching elements 21 and 22 having a relatively high heat generation temperature among the plurality of switching elements 20.

The inspection method for inspecting the electronic device 1 of the present embodiment has the following effects.
(6) In the present embodiment, when the difference between the first acquisition temperature and the second acquisition temperature is larger than the predetermined threshold value α in the upper limit threshold setting step, the upper limit threshold value Tth_max used in the inspection step is set.
As a result, it is possible to secure a large temperature difference between the first acquisition temperature and the upper limit threshold value Tth_max. Therefore, even if there is a tolerance in the temperature characteristics of the predetermined electronic device 1 to be inspected in the inspection step, it is possible to absorb the intersection by the temperature difference between the first acquisition temperature and the upper limit threshold value Tth_max. Therefore, according to this inspection method, it is possible to suppress erroneous detection regarding the inspection of the heat dissipation function of the heat dissipation gel 33 included in the predetermined electronic device 1.

(7) In the present embodiment, when the difference between the first acquisition temperature and the second acquisition temperature is smaller than the predetermined threshold value α in the current pattern change step, the current pattern supplied to the switching element 20 of the electronic device 1 is changed. To do.
Thereby, it is possible to select a current pattern in which the difference between the first acquisition temperature and the second acquisition temperature is larger than a predetermined threshold value α, that is, an appropriate current pattern used for the inspection.

[Second Embodiment]
A second embodiment of the present invention is shown in FIG. In the following description, the same reference numerals will be given to the configurations substantially the same as those of the first embodiment described above, and the description thereof will be omitted.
In the second embodiment, the two switching elements 21 and 22, which have a relatively high heat generation temperature among the four switching elements 20, are arranged side by side in the longitudinal direction of the substrate 10 on the opposite side of the connector 28. Therefore, the thermistor 50 is mounted so as to sandwich the substrate 10 at positions close to the two switching elements 21 and 22. As a result, the electronic device 1 of the second embodiment also accurately detects the temperature of the switching elements 21 and 22 by the output of the thermistor 50 and supplies the current amount to all the switching elements 20 as in the first embodiment. Can be appropriately restricted.

[Third Embodiment]
A third embodiment of the present invention is shown in FIG. In the third embodiment, two switching elements 21 and 22 having a relatively high heat generation temperature among the four switching elements 20 are arranged side by side in the lateral direction of the substrate 10 near the center in the longitudinal direction of the substrate 10. ing. Therefore, the thermistor 50 is mounted so as to sandwich the substrate 10 at positions close to the two switching elements 21 and 22. As a result, the electronic device 1 of the third embodiment also accurately detects the temperature of the switching elements 21 and 22 by the output of the thermistor 50 and supplies the temperature to all the switching elements 20 as in the first and second embodiments. The amount of current to be generated can be appropriately limited.

(Other embodiments)
(1) In the above-described embodiment, the electronic device 1 that drives and controls the motor 2 used in the electric power steering device of the vehicle has been described as an example. On the other hand, in another embodiment, the electronic device 1 is applicable not only to driving the motor 2 but also to controlling various products.

(2) In the above-described embodiment, the switching element 20 has been described by taking the one constituting the H-bridge circuit as an example. On the other hand, in another embodiment, the switching element 20 may constitute various circuits such as a three-phase inverter circuit, or may simply turn on / off the energization.

(3) In the above-described embodiment, a plurality of switching elements 20 and shunt resistors 25 as a plurality of heat generating components are collectively arranged on a part of the substrate 10. On the other hand, in another embodiment, the plurality of switching elements 20 and the shunt resistors 25 as the plurality of heat generating components may be arranged at any position on the substrate 10 or may be dispersedly arranged on the substrate 10. Good. Further, among the plurality of heat-generating components, some of the heat-generating components may be arranged on the first surface 11 of the substrate 10, and the remaining heat-generating components may be arranged on the second surface 12 of the substrate 10. That is, in the present invention, there is no limitation on the position where a plurality of heat generating components are arranged on the substrate.
Even in this case, in the present invention, it is sufficient that the positional relationship is established in which the temperature detection element is provided near the heat generating component having a relatively high heat generating temperature among the plurality of heat generating components installed on the substrate.

(4) In the above-described embodiment, the thermistor 50 has been described as an example of the temperature detecting element. On the other hand, in other embodiments, the temperature detection element can use various elements such as a platinum resistance temperature detector.

(5) In the above-described embodiment, a switching element 20 such as a MOSFET or an IGBT and a shunt resistor 25 have been described as examples as heat generating components. On the other hand, in other embodiments, the heat generating component may be, for example, a capacitor 26 or a coil 29.

(6) In the above-described embodiment, the heat radiating gel 33 has been described as an example as the heat conductive material. On the other hand, in other embodiments, the heat conductive material may be, for example, a heat radiating sheet or a heat radiating grease.
As described above, the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the invention.

1 ... Electronic device 10 ... Substrate 20 ... Switching element (heat generating component)
30 ... Heat sink 33 ... Heat dissipation gel (heat conductive material)
40 ... Microcomputer (detector)
50 ... Thermistor (temperature detection element)

Claims (5)

A substrate (10) , a plurality of heat-generating components (20 to 25) mounted on the substrate, a heat sink (30) provided on the opposite side of the heat-generating component from the substrate, and between the heat-generating component and the heat sink. The heat conductive material (33) filled in the above, and the surface (12) opposite to the surface (11) in which the heat conductive material is filled in the substrate, the heat generating temperature is relatively high among the plurality of heat generating parts. The electronic device (1) including a temperature detection element (50) provided near the heat generating component (21, 22) and a detection unit (40) capable of detecting the temperature by the output of the temperature detection element. It is an inspection method that can inspect the heat dissipation function of the heat conductive material.
In the first reference product having the configuration of the electronic device, the first temperature acquisition step (S2) for acquiring the temperature detected by the detection unit when power is supplied to the heat generating component in a predetermined current pattern,
In the second reference product in which the heat conductive material is removed from the configuration of the electronic device, a second temperature acquisition step of acquiring the temperature detected by the detection unit when power is supplied to the heat generating component in a predetermined current pattern. (S3) and
A determination step (S4) for determining whether or not the difference (M, N) between the temperature acquired in the first temperature acquisition step and the temperature acquired in the second temperature acquisition step is larger than a predetermined threshold value (α). When,
When the difference between the temperature acquired in the first temperature acquisition step and the temperature acquired in the second temperature acquisition step is larger than the predetermined threshold value, the temperature detected in the first temperature acquisition step and the second temperature acquisition The upper limit threshold setting step (S6) for setting the upper limit threshold value (Tth_max) at the temperature between the temperature detected in the step and
In the inspection product having the configuration of the electronic device, power is supplied to the heat generating component in the predetermined current pattern, and whether or not the temperature detected by the detection unit included in the inspection product is lower than the upper limit threshold value is determined. A method for inspecting an electronic device including an inspection step (S11) to be inspected. When the difference between the temperature acquired in the first temperature acquisition step and the temperature acquired in the second temperature acquisition step is smaller than the predetermined threshold value, the electrons in the first temperature acquisition step and the second temperature acquisition step. The method for inspecting an electronic device according to claim 1 , further comprising a current pattern changing step (S7) for changing the current pattern supplied to the heat generating component of the device. 1. The substrate of the electronic device includes a heat receiving wiring pattern (51) on which the temperature detection element is mounted on a surface opposite to the surface on which the heat generating component having a relatively high heat generation temperature is mounted. Alternatively, the method for inspecting an electronic device according to 2 . The heat receiving wiring pattern of the electronic device is located at a position facing the power wiring pattern (14) to which the drain terminals (21,221) or source terminals (212, 222) of the heat generating component having a relatively high heat generation temperature are connected. The method for inspecting an electronic device according to claim 3 , which is provided in 1. The heat receiving wiring pattern of the electronic device straddles the plurality of power wiring patterns at positions facing the plurality of power wiring patterns to which the drain terminals or source terminals of the plurality of heat generating components having a high heat generation temperature are connected. The method for inspecting an electronic device according to claim 3 or 4 , wherein the method is provided .

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